Field Transmitter: Pressure Sensor

Field Transmitter: Pressure Sensor Solutions from Texas Instruments.

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Design Considerations

Field Transmitter: Pressure Sensor

Pressure Sensor solutions are used to measure pressure of gases/liquids and have a wide range of uses in industrial, commercial applications. Pressure measurements typically are made as absolute, gauge or differential (or relative) measurements. Absolute pressure sensors measure a pressure relative to a vacuum, gauge sensors measure a pressure relative to atmospheric pressure, and differential sensors measure a pressure difference between two inputs.

Excitation Technique: The bridge sensor needs an accurate and highly stable excitation source. It is a common design practice to employ Ratiometric measurement techniques- use the same common reference for the excitation circuitry and the ADC for better. TI's Reference Voltages have high initial accuracy and extremely low temperature drift and are ideally suited for bridge excitation.

Signal Conditioning: In most pressure sensors the output range of a pressure sensor is very small and thus the signal needs to be amplified before processing to prevent introduction of errors. TI provides a wide selection of Low Noise Amplifiers with high CMRR and high gain at low frequencies suitable for the small signal output of the sensor. Additionally, since the signal bandwidth is low, the 1/f noise of the amplifiers can introduce errors. TI's Chopper-stabilization amplifiers provide extremely high dc precision and noise performance at low frequency range.

TI has highly integrated solutions tailored for bridge pressure sensors. This single chip solution consists of precision, low-drift programmable gain instrumentation amplifiers using auto-zero techniques, linearization circuitry, temperature compensation scheme, programmable fault monitors and over/under scale limiters.

Signal Acquisition and Processing: TI’s high resolution differential ADCs have low power consumption, wide dynamic range and low noise. This can be used to digitize the conditioned analog bridge output for high resolution, precision measurements. Alternately, one could use TI's MSP430 microcontrollers with integrated ADCs and DACs. Further post processing algorithms can be run on this MCU.

Interface and Communication: Traditional analog (4 - 20mA) interface remains the popular choice for industrial control and sensor applications. The other popular protocols include HART, Profibus and IO-Link. TI's IO-Link interface products have integrated regulators and diagnostic outputs. In addition, wireless options based on IEEE 802.15.4 protocols are becoming more prevalent. TI is committed to provide solutions for both traditional and emerging industrial interfaces.

Power Management: The Field Transmitter can be powered in one of three ways. Line powered transmitters are commonly powered by voltage rails of 12V, or 24V. Loop powered transmitters are powered by the 4-20 mA loop. Such transmitters require extremely low power architectures as the entire solutions has to be powered off the loop. TI provides high efficiency Step Down converters with low quiescent current and low output ripple appropriate for Line and Loop powered transmitters. Battery powered transmitters powered can be designed using TI's low power Buck and Buck-Boost converters. The DC/DC buck converters offer over 95% efficiency over a wide battery voltage range, even with input voltage down to 1.8 volts extending battery life. Special Buck-Boost converters generate a stable required output voltage and supply constant current for over- and under-input voltage conditions and support various battery configurations.

Microcontroller: The Hercules™ Safety MCUs offer an ARM Cortex-R4F based solution and are certified suitable for use in systems that need to achieve IEC61508 SIL-3 safety levels. These MCUs also offer integrated floating point, 12 bit ADCs, motor-control-specific PWMs and encoder inputs via its flexible HET Timer co-processor. Hercules Safety MCUs can also be used to implement scalar and vector-control techniques and support a range of performance requirements.

Application Notes (13)

Title Abstract Type Size (KB) Date Views
HTM 8 KB 09 Oct 2011 3028
HTM 9 KB 21 Sep 2009 1845
HTM 8 KB 02 Jan 2008 285
HTM 8 KB 29 Mar 2007 948
HTM 8 KB 20 Apr 2006 347
HTM 8 KB 13 Jan 2006 250
HTM 8 KB 28 Nov 2005 343
PDF 177 KB 10 Oct 2005 925
HTM 9 KB 28 Jun 2005 198
HTM 8 KB 08 Mar 2005 368
HTM 8 KB 15 Nov 2004 402
HTM 8 KB 24 May 2004 11592
HTM 8 KB 21 Jan 2000 834
    

Reference Designs

Description Part Number Company Tool Type
CC1100EM 315-433MHz Reference Design CC1100EM433_REFDES Texas Instruments Reference Designs
CC1101EM 868 and 915MHz Reference Design CC1101EM868-915_REFDES Texas Instruments Reference Designs
CC1150EM 315-433MHz Reference Design CC1150EM433_REFDES Texas Instruments Reference Designs
CC1150EM 868-915Mhz Reference Design CC1150EM868_REFDES Texas Instruments Reference Designs
CC2500 Reference Design (62 mil layer spacing) CC2500_REFDES_062 Texas Instruments Reference Designs
CC2500EM Reference Design CC2500EM_REFDES Texas Instruments Reference Designs

Selection and Solution Guides

Selection Guides (6)

Title Abstract Type Size (KB) Date Views
PDF 169 KB 28 Jul 2014 1056
PDF 9.51 MB 01 May 2014 24034
PDF 273 KB 16 Jul 2012 1056
PDF 302 KB 28 Mar 2012 1481
PDF 916 KB 22 Mar 2011 109
PDF 175 KB 11 Jun 2010 1239

Solution Guides (6)

Title Abstract Type Size (KB) Date Views
PDF 5.83 MB 26 Jan 2014 13037
PDF 4.07 MB 12 Nov 2013 3158
PDF 896 KB 12 Nov 2013 3663
PDF 1.08 MB 31 Oct 2013 4041
PDF 599 KB 30 Oct 2013 2125
PDF 2.13 MB 30 Oct 2013 1480

Tools and Software

Name Part # Company Software/Tool Type
CC1101 Development Kit 868-915MHz CC1101DK868-915 Texas Instruments Development Kits
CC2520 Evaluation Module Kit CC2520EMK Texas Instruments Daughter Cards
Code Composer Studio (CCS) Integrated Development Environment (IDE) CCSTUDIO Texas Instruments SW Development Tools, IDEs, Compilers
DAC7311 Evaluation Module DAC7311EVM Texas Instruments Evaluation Modules & Boards
MSP430 USB Stick Development Tool EZ430-F2013 Texas Instruments Evaluation Modules & Boards

Product Bulletin & White Papers

Product Bulletin (1)

Title Abstract Type Size (MB) Date Views
PDF 299 KB 14 Aug 2013 1302

White Papers (3)

Title Abstract Type Size (MB) Date Views
PDF 905 KB 31 Jul 2014 3139
PDF 658 KB 09 Jul 2014 3024
PDF 393 KB 27 Jun 2014 12150

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